Lug strap



Aug. 27, 1940. H. F. WEBSTER LUG STRAP Filed Oct. 4. 1938 INVENTOR Patented Aug. 27, 1940 or, i

' relates to improvements in such a lug LUG STRAP I 1 Harry F. .WebstenfWarren, ()l1io Application October 4, 1938, Scrial No."233,Z00. fi

1 -This inventionrelates to improvements in lug straps of a laminated construction wherein superimposed plies of fabric are united by a bonding material; 'More particularly the invention strap constructed of rubberized fabric. 1 V

Important objects of the invention are, to provide 9. lug strap of the aforesaid type constructed to give it great durability, and provide such a strap 'designedfor economical manufacture.

Other objects of the invention will appear hereinafter. I 1 In the drawing,

Fig. 1 is a;perspectiveviewshowing a step in the manufacture "of the improved lugstrap; Fig. 2f isa perspective view showing another step of said manufacture;

- Fig. 3 is aperspective view of. a filler block I x V approximately cubic'al' form.

employed in the lug strap construction;

Fig. 4 is aview of a double lug strap structure preparedfor molding. l

Fig. 5 is a longitudinal sectional view illustrating the molding of a double strap;

Fig. 6 is a transverse section on the line 66 ,of

Fig. 5;

Fig. 7 is a perspective viewof a mold core employed in the molding of the double'strap; and

Fig. 8 is a perspective View of a finished lug strap. a i

In the manufacture of lug straps embodying the improved construction there is employed a" wide sheet I of strong square-woven textile fab-,,

I defined by placing two U-shaped lug straps end to end. As the sheet is wound it is kept taut for smoothness and close contact of its coils. Winding is continued to form a number of superimposed plies sufficient to build-up thestructure to a thickness exceeding the desired thickness of the longitudinal side members or legs of a fin- The The wound of lug straps arranged-end 'to'endl "Preferably the width of each partly formed double strap '5,

width Or finished strap A number of sheets 6 of'strong' textile fabric are coated t' on both'sides with a bondinginat'e rial. Preferably this mate'rial is also a rubber composition similar 7 to that upon the; sheet I: The rubberized sheets 6 are superimposed smoothlyv one upon another ine. required number to produce a m'ulti -ply sheet having a thickness approximately equalto the inside width of the between the lines l, slightly exceeds the"=desir ed loopdefined by onejofthe aforesaid double straps. The s'heet's'j fi are smoothed and pressed'together by rolling or 3 otherwise? Next said muIti pIy sheet is severed along "s'paced 'parallel lines I and along spaced par'allel cross lines-"8 I to divide th'e sheet; into a multitudebf multie ply bl'oclrsilliof A pair of the"blocl' "s'9,-withtheir' bonding'niate; rial still" uncured; are fitted within. the opposite ends or bows of one of the double straps 5 in such position that the'plies 9 of the blocks are parallel to the side members of the strap, and the opposite sides of the blocks are flush with the opposite side edges of the strap.

The double strap, with the inserted filler blocks is next molded and vulcanized. In preparation for molding, a mold core Ill of steelis fitted into the loop defined by the strap. This core should have the precise shape and dimensions desired for theinterior of the molded strap. As shown, the core has flat sides and concave end surfaces l I. These concave surfaces are engaged with the inner or forward surfaces of the blocks 9. The strap, with. the core inserted, is placed between opposed block-like sections l2 of a split mold. Said mold sections have, in their opposed faces,

These cavities are elongated, 1 v

similar cavities l3. have flat sides and. rounded ends, and conform exactly to the shape and dimensions desired for the molded strap. The plane of separation of the mold sections is at the center of .the bows or ends of the looped strap. The molding operation is performed under heat and pressure to vulcanize the rubber composition to a preliminary soft rubber state. Under the heat and pressure the rubber composition of the filler blocks unites with strap and the filler blocks are permanently united to form an integral double lug strap unit. The

vforwardsurfaces M of the blocks are also molded to convex curvature by the concave ends of the mold core.

After said molding and preliminary vulcanizathat of the strap, and all of the plies forming the tion the strap and core II] are removed from the mold, the core I0 is removed from the strap, the strap is cooled, and excess, overflow rubber is trimmed off. The double strap is severed at the middle of its length to form two single straps S, one of which is shown in Fig. 8. The ends of the legs of the strap are cut to a rounded form and, either before or after severance, the usual slots I5 are cut in the sidemembers or legs of the strap. Finally the vulcanization of the rubber is completed to bring it to a hard state. This may be done by subjecting the completely formed straps to dry heat in a suitable oven.

The lug strap, so produced, has a thickened,

reinforced bow structure to withstand impact with the picker stick. The reinforcement is a permanent, integral part of the strap and the arrangement of the plies 9 contributes materially to wear resistance. Said plies impact the picker stick edgewise, which is superior to broad side impact because then the'picker stick would,

Wear through the thickness of the plies and fray the impact surface. The convexity of said surface enables it to make rolling contact with the picker stick. Since the fabric employed throughout the, structure of the strap is coated upon both sides withthe rubber compositionand since the composition is confined in the molding operation the finished strap contains much more of the composition than is required for mere bonding. It-comprises a large part of the strap and forms a-matrix extending, throughout the entire strap and enveloping all of the fabric. hard, tough, resilient and moisture-impervious. It surrounds the individual threads of the fabric and is reinforced throughoutpthe legs and the thickened'bow of the strap by the fabric plies.

1 :It is common practice'in lug strap construction to first ,completely form the U-shaped body of the vstrap'and then insert within the bow of the strap a separately formed plug to serve-as an This matrix is abutment for the picker stick. Said plug is rivetted in place with consequent weakening of both the strap and the plug. My invention avoids this objectionable construction and provides a durable, one-piece, molded lug strap adequately reinforced to resist wear from the picker stick and inexpensive to manufacture.

What I claim is:

A lug strap comprising numerous superimposed long plies of rubberized fabricv all 7 extending widthwise from edge to'edge of the strap and extending longitudinally in U-form and in nested relation and bonded together in succession by the rubber to form the legs and bow of the strap,

and numerous superimposed short plies of rubberized fabric nested within the bow and between the portions of the legs adjacent the bow and forming a filler increasing the fore-and-aft thickness of the bow, all of said filler plies extending substantially the full width of the strap between the edges of the latter and all lying substantial y parallel to the plies in the legs of the strapand bonded together in succession by therubber and with their outermost plies bonded by the rubber to the inner faces of the legs and their rear edges bonded by the rubber to the inner face of the bow and with their forward edges disposed torform an abutment to engage therpicker'stick, said ilegs, bow and filler being permanently united by molding and vulcanization into a solid, hard rubber mass with parallel layers of fabric embedded in the rubber and extending side'by side] throughout the legs'and the reinforcement in the bow, with the edges of the fabric layers in, said reinforcements in position to engage the picker-stick edge-on, to form a onepiece integral lug strap structure with the filler held in place solely by the molded and Vulcanized rubber. I

y HARRY F. WEBSTER. 

